Telephone system



May 19, 1931. R. MERCER TELEPHONE SYSTEM 0 Fi led Feb. 26, 1327 2 Sheets-Sheet 1 lnuen m" Emhavd Mercer May 19, 1931. MERCER 1,805,778

' TELEPHONE SYSTEM Filed Feb. 26, 1927 2 Sheets-Sheet 2 ;.QJFUNITED PATENT; orrica f 1 men Ann. Assmnoa TO nssocm'rnn rumour a new names. or p e p I m nus on'v, inssoum, a. GOIPAJSY ting from up which will meet network. Where there are considerably less May 19. 1931 p, y 7

'roim' mm or nmwm 1 5m a bri as, 1937; Serial at. 171,119, and in emit Britain. larch as, me.

The present invention relates to improvements in or relati to telephone systems and v while it more particularly applies to the systems employing register trans be understood that it is not exclusively l1m- I ators, it should ited thereto. a

It has been proposed in large networks to arrange for the directory number which is dialled by a callin subscriber in calling another, to consist o first three letters of the name of the exchange to which the wanted partys line is connect- .ed and four figures. For this purpose the dial'switch is provided with two or three letters in the various finger holds, a figure. Normall therewould a prommately 1000 com inations in whic these three digits could bearrange'd but obviously there are certain limitations in practice, one of which is that it is undesirable to have .any letters in the fingerhold 1, unless the letter I, and only one O'in the finger hold 0, and further that the possible number of-combinations capable 0 forming part of exchange names is very much less than the number of combinations which may be obtained. Actually to 100 to 200 exchange names these conditions in a given exchanges in a network than 100 it is notessential to use three digits of'the exchange name, and accordingly it has been proposed to use two. Thisenables the register translator apparatus to be considerably simplified.

.. For instance, in the patent to Richardson et 211., 1,702,392, Feb. 19, 1929, the first digit of an exchange name is caused to operate what is known as an A digit selector. This switch responds to the first digitand then selects an idle registertranslator where the next two digits are stored, the whole three I digits are then translated in a suitable manner. In a two digit. area it is possible to eliminate the first set of switches shown as A digit selectorsand thereby effect a considerable economy. I

One of the great advantages of a system employing three digits to correspond to the exchange required is thatthese three digits.

three letters, namely theas well as however there is no difiiculty in getusually lend themselves to a simple pronunciation which further assists the memory in addition to the factor that these are the first three letters ofthe exchangename; secondly,

Eprsons who are likel to use the telephone th in two digit an three digit areas are qulte likely to'make a mistake and dial an extra digit, or a digit short, when in the i wrong area. connecting to a wrong number with natural annoyance tothe party disturbed, or not connecting to any number at all. Thirdly, a

telephone network may develop to such a size that the addition of further exchanges will necessitate the conversion froma twodigitscribers into makinguse of'the third letter of the exchange name.

The object of the present invention is to avoid all these disadvantages, while retaining the economical advantages of a .two digit This would result either in.

register translator for a greater number of exchan es than is now possible, and according to t e principal feature of the invention,

arrangements are provided in a two digitarea for arranging that the subscriber must dial .three digits and arranging for one of the digits either to be suppressed orto be routed away from the'normal receiving apparatus. Ow-

ing to the fact that there are only five vowels,

and in a large majority of exchange namesthe second digit tends to'be a vowel, it will happen that in areas where two digits are dialled by a callin subscriber, the limitation of the numher 0 exchan e names available will be less I if the first an thirddigit is used to distin guish the exchange name, than if the second was used in conjunction with either of the others. For instance'it has been found in the London area, takinglOl exchange names of which the firstthree letters when dialled by the dial adopted for the London area will give i 101 different signals, that if only the first two letters are used the 101 exchange names will rst and third letters are used 54 difierent sig-v nals-are given. Consequently it may become necessary to convert an area and install the give only 43 difl'erent signals, whereas if the extra apparatus required at a very much e active on the registering apparatus and the second digit suppressed.

Accordingly a second feature of the present invention is to arrange for the suppression of the second digit of the exchange name dialled by a subscriber. It should be understood thatit will be necessary to modify in any network not only the arrangements which respond to the impulses dialled by a calling subscriber, but also the operators impulse senders where these are operated on a similar code to the subscriber as regard the exchange name. In the accompanying drawings arrangements are shown which relate to arrangements which respond to impulses dialled by a calling subscriber, but it will be clear to those versed in thee-rt that a modification could be made to an operators control impulse sending arrangement, such for instance, as is described in the patent to Gil-- lings, 1,705,832, March 19, 1929, by a somewhat similar arrangement, modified only in that a key pressing operation is rendered nonefi'ective instead of a series of impulses.

The accompahying drawings, Figs. 1 and 2, illustrate two alternative arrangements of carrying the invention into eifect. These drawings show only that part of the apparatus which requires altering from standard. constructions. As an example of such con-.

structions, the patent to Bellamy et 211., 1,683,857, Sept. 11, 1928, is referred to, and it will be found that Fig. 1 of the present drawings substantially corresponds to Fig. 2 of the drawings shown in the above-mentioned specification. Fig. 2 is similar and corresponds to the left-hand side of Fig. 1.

.In the first place reference will be had to Fig. 1 and the operation of the switch S will be briefly described, all other particulars be ing obtainable by reference to the said patent to Bellamy et al., although this is not necessary for an understanding of the present invention as arrangements such as the switch S are common to all systems of this type.

To describe the operation of the invention with relation to this figure, it will be suflicient to refer to the operation of the system but this need only be done in a general way. For this purpose when the subscriber operates his dial for the first letter, impulses are sent over the lead 7 5, which pass over the slow acting relay 102, wiper 107, the second contact, terminal 5 of the terminal block TB to terminal 1 and I thence over the lead 121 to the vertical magnet of the registering switch.

It will be assumed in this case only a two digit system is being described, as is shown in the above patent to Bellamy et a1. Relay 102 energizes inthis circuit-and thereby en ergizes relay 101. At the end of a series of impulses, relay 102 de-energizes and comnaomva that the next series of impulses is routed over lead 75, relay 102, wiper 107, contact 6,

contact 3 to lead 122 and thence to the second or rotary magnet of the register switch so that the second digit is recorded. At the end of the series of impulses the magnet 103 steps as before to connect earth to lead 114: to initiate the impulse sending and permits a subsequent series of impulses to be sent over lead 131, 132, 133 and 134 successively. When it is desired to restore the switch S to normal, earth is connected to the lead 113, whereupon the release magnet 10a energizes and restores the switch to normal. In the present case the switch S has been provided with one additional contact position, and with adjustable means AM to prevent the switch restoring to the additional contact so that as shown, this contact is entirely out of action. Gonsequently as has been described, the modification so far makes no difference Whatever to the o eration as described in connection with the ellamy et al. patent. Assume however that it is desired to modify the director so'as to receive three letters and to suppress the second, then the adjusting means AM for the wipers are modified so that the normal position is such that the normal or additional contact is connected to by wipers 106 and 107 when in the normal position, and in consequence of which the first series of impulses is received, that is from 'over lead 75, relay 102, wiper 107, contact 4, contact 1,terminal block TB to lead 121 and thence to the rotary magnet. The second series of impulses passes over lead 75, relay 102, wiper 107, contact 5, contact 2. resistance 7 back to battery. This series of impulses therefore is routed away from and has no effect upon the normal registering apparatus. The third series of impulses then passes over the patch 75, relay 102, wiper 107, terminal 6, terminal 3, lead 122 to the second or rotarymagnet of the register. Consequently the first and third digits operate the registering mechanism. The arrangement for restoring to normal is the same as before, but the wiper 106 does not become effective to control the transmission of impulses until the third digit has been sent. This is necessary as the transmission of impulses should not commence and does not commence until after the three letters of the exchange name have been received.

It will thus be appreciated that by a simple mechanical modification the switch S can respond to either two or three digits and effect appropriate control accordingly. All that is necessar is to modify the connections at the termina end and to modify the normal position of the wipersboth of which can be done very rapidly.

.the wi ers '15 I p Y In Fig. 2 the switch S2 is similar to the switch S as re ards its operating function but differs in t at while the switch S is 'a switch which moves in one direction againstspring-pressure and is restored to normal by theoperation of the release magnet, and the restoring spring, the switch S2 moves con,- tinuously forward so that one arm of a lurality with. which each wiper is provide isalwa sengaging with a contact. In placeof -normal springs, and additional contact bank and wiper 8 is provided. Thewi'pers are given the same reference letters as 106 and 107 because their function is identical with that described in Fig. 1. The terminal block however is slightly increased in size as all the modifications necessary can be effected thereat. Where the reg ister has to respond to two digits and to record two digits, the contacts 9 and 12 are connected together as well as contacts 11'and 14, consequently when earth is placed on conductor, 113 the wiper 8 will move to rest on the second contact, which is. insulated,

contact 13 not being connected up. If however, it is desired to receive three impulses and the register mechanism has only to respond to two, namely the first and third,

" then contacts and 13 and .11 and 14 are connected up and the wiper 8 will then move into the position shown in the drawings if earth is connected to lead 113, and the wiper is resting in any osition other than the posi-.

tion shown. It oes not appear to be necessary to describe the other part of the apparatus which is, as previously stated, identical with that shown in Fig. 1.

It is of course clear that 1f for any reasonit may be desirable to suppress the first letter or the third letter in place of the second, this-could be readily effected, although it is believed that the arrangement shown would probably prove in practice to be that most desirable, that is the arrangement by which three impulse series'are received and the first and third are utilized until the second is required.

Letters Patent is What I claim as new and desire to secure by.

1. A telephone system in which the initial letters of names of exchanges in a network are transmitted to receiving apparatus in the same manner as the numbers of Wanted subscribers, characterized in thatthe receiving apparatus is provided with terminal arrange.-

ments in a readily accessible position with connections thereto so arranged that by modifying the inter-connections between the terminals the receiving arrangements can .re-

spond to either two or-three initial letters of names of the exchanges in accordance with the number of exchanges in the network.

2. Aregister sender for use in telephone systems adapted to receive a plurality of series of impulses corresponding to the letters of an exchange name, to suppress one or more of said letters, and to'record the'remaining y letter or'letters.

3. A regist'ersender adapted to respond to either -'two' or three series of impulses and provided with a terminal block by which a particular two of thethree-series of the im- I I pulses may be made efiective or two series may be'made effective when three'letters are u received. 4. In a telephone system in which initial letters of names of exc anges are transmitted in the same manner as the numbers of desired subscribers and in which the transmitted letters and numbers are received b the registering apparatus of switch-contro ling register senders, letter-registering means included int-he registering portion of the register senders for registering one less letter than is received, and'means included in the registering apparatus for absorbing, without registering, the other received letter.

5. In a multi-ofiice telephone systemin which thev com lete number ofa subscriber comprises the rst three letters. of an oflice name followed by the digits necessar to' distinguish the line of that subscriber rom the I of a su 'scriber includes the first three letters of the name of the ofiice in which his line terminates, aninput-control switch arranged to shift the registering circuit after each digit, register devices connected to each position of said input-control'switch exce t the second, and circuit arrangements for a vaneing said impulse control switch through its second position responsive to the receipt of l the second letter of the ofiice name.

7. In a registering device including a twomotion register for use in a telephone system wherein the first three characters in a number are the first three letters in an ofiice' name, means for operating said register in its firstmotion to record the first character of a number, for receiving the second character of the number, and for operating said registering device in its second motionto register the third character in the number.

v 8. In a registering device having associated therewith a'multi-position sequence switch.

means responsive to the receipt of trains of im ulses for suitably advancing said sequence switch so that it is in its first position while ing and retransmitting apparatus is provided to receive and register characters in telephone designations and to control automatic switching apparatus to set up connections, means ,7

portion of the included in the registerin registering and retransmittmg apparatus for registerin' one less character than is received in a set 0% characters, and means associated with the said registering apparatus for. absorbing, without registering, the other received character.

10. In a device arranged to register a plurality of groups of electrical impulses, a separate receiving conductor for each group of impulses, a distributing device having a normal position and having arrangementsassociated therewith for advancing it between groups of im ulses to direct the groups of impulses to t c said receiving conductors, and means for mechanically altering said distributing switch so that one of the off-normal positions thereof becomes its normal position.

11. A progressively-movable, impulseoperated, step-by-step switch arranged to be operated from a normal position into a particular off-normal position corresponding to the number of received impulsespmeans for retracting said switch to its normal position, and means for adjusting said switch so that thenormal position thereof in one adjust-- ment corresponds to an off-normal position of the switch in a different adjustment.

12. In a registering apparatus containing a plurality of registering devices, a circuit path over which a plurality of series of impulses are received, means for directing successive series of impulses to separate registering devices and for directing one series of impulses so that it does not reach any registering device.

13. In combination, registerin devices each arranged to register aseries o? impulses and a non-registering device, an impulse distributor, and means for operating said distributor between series of impulses so that a pluralityof series of impulses are-directed to a like plurality of said registering devices and one series of impulses is directed to said non-registering device.

14. In combination, registering devices each arranged to register a series of impulses, an impulse distributor arranged to distribute series of impulses to said devlces successively, conductors extending from said distributor to said devices, and cross-connecting means'in terposed in said conductors between said distributor and said devices.

15. In a telephone system wherein impulse series corresponding tocharacters in teleand means for adjusting the absorbing means to absorb series.

- 17.111 combination, means for transmit-- ting a lurality of series of impulses, and means ior absorbing or nullifying any desired one of said series.

any desired one of a plurality of 18. In combination, means for receiving aplurality of impulse series, and means for absorbing or nullifying any desired series of received impulses.

19. A telephone system in which initial letters of names of exchanges are transmittedin the same manner as the numbers of wanted subscribers, characterized in that the receiving apparatus is provided with means for suppressing one or more of the letters transmitted thereto so that-such letter or letters are rendered non-effective in controlling the setting up of a connection, the transmitted letters being received on a register which controls the transmission of impulses by an impulse sender according to a code having no numerical relationship to the impulses received.

20. A telephone system in which initial letters of names of exchanges are transmitted in thesame manner as the numbers of wanted subscribersand in which receiving apparatus is provided common to a plurality of trunk lines, characterized in that the receiving apparatus is provided with means for suppressing one or more of the letters transmitted thereto so that such letter or letters are rendered non-effective in controlling the setting up of a connection, the transmitted letters being received on a register which controls the transmission of impulses by an impulse sender according to a code having no numerical relationship to the impulses received, said register being adapted to receive three transmitted letters and to record only two.

In testimony whereof I hereunto aflix my 

